The Durability Factor with Cold-Applied versus Hot-Applied Liquid Waterproofing By Greg Austin
Introduction There are many obvious reasons why durability is important for com- mercial construction and the waterproofing of covered podiums and plaza decks, green roofs, balconies, and terraces. Most of these public areas need to withstand foot traffic, vehicles, and equipment transport. In all cases, especially with roofs, specifiers need to ensure there is a reliable, highly durable membrane sealing the surface and any design features to provide long-term water protection. Commercial builders, designers, and architects can choose from nu - merous different types of waterproofing products. Liquid-applied is typically preferred when conformation to the given site layout and/ or speed of installation are critical. There are two types of liquid wa - terproofing – cold-applied and hot-applied – each of them has its own set of features and benefits. In addition, the total amount of material needed to provide a reliable waterproofing layer should be considered. So, which type of liquid waterproofing is more durable? After looking at the durability factors in waterproofing, we will explore the differ - ences between cold and hot-applied waterproofing, concluding which liquid waterproofing type is recommended based on those all-important durability factors. The Durability Factors in Liquid Waterproofing There are six major criteria that should be considered when assessing the durability performance of a component product and system overall, five of which are defined through ASTM International standard test - ing methods. Formerly known as the American Society for Testing and Materials, ASTM is a standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. The six testing criteria for vulcanized rubber and thermoplastic elas - tomers (the materials that hot-applied and cold-applied liquid water - proofing solutions are made of respectively) are as follows: 1. Tensile (tension) strength (ASTM D412) – The ability to withstand tensile forces. Tensile strength measures the stress required to stretch the material to the point where it breaks. It can be used to evaluate the maximum amount of tensile force that a material can be subject to before failure. 2. Tear resistance or tear strength (ASTM D624) – The resistance to tearing action, including the force to initiate tearing of the materials or tear propa- gation. With a waterproofing application, the force to initiate the tearing is particularly important.
3. Adhesion to concrete (ASTM D4541/ASTM D7234) – The greatest perpendicular force a surface area can bear before a section of material is “pulled off” or detached. How well the material adheres to the concrete and maintains after water immersion is very critical with liquid waterproofing. 4. Shore hardness (ASTM D2240) – The resistance a material has to inden- tation. This measures the indentation hardness of substances such as ther- moplastic elastomers, vulcanized (thermoset) rubber, elastomeric materials, and some plastics. 5. Abrasion resistance (ASTM D4060 - Taber Wear Index) – The rate of wear as calculated by measuring the loss in weight (in milligrams) per thousand cycles of abrasion. The lower the wear index, the better the abrasion resistance. 6. Low-temperature crack bridging (ASTM C836 or ASTM C1305) – The abil- ity of the material to maintain its integrity while bridging a crack in the substrate at low ambient temperatures when the polymeric materials are least likely to be flexible. Meeting this criterion allows the material to perform exceptionally at crack-bridging, a critical factor with construction-based waterproofing. A waterproofing system should be evaluated on the basis of the re - sults of this set of tests and should not be selected based on a single performance value. Importantly, the highest possible test value does not always translate into installed performance. Therefore the system should be evaluated in total to determine the likelihood of achieving the desired installed performance. Notable Durability Differences Between Cold-Applied and Hot-Applied Waterproofing Product materials and chemistry Hot-applied liquid waterproofing systems consist of rubberized as - phalt. Multiple layers must be applied to achieve durability, along with a reinforcement layer made of fleece and a protection board, which add complexity to the installation. Because of the additional skill set required for the installation of reinforcement and protection, there is a greater chance of errors occurring during the installation that could affect the watertight performance and durability of the product. Cold-applied liquid waterproofing requires applying only one or two layers (after the primer) to achieve durable performance. Some of these systems do not require a reinforcement layer or protection course during construction.
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